In order to improve the handling properties of the dough and/or the final properties of the baked products there is a continuous effort to develop processing aids with improving properties. Processing aids are defined herein as compounds that improve the handling properties of the dough and/or the final properties of the baked products. Dough properties that may be improved comprise stability, machineability, gas retaining capability, reduced blistering, reduced stickiness, elasticity, extensibility, moldability etcetera. Properties of the baked products that may be improved comprise loaf volume, crust crispiness, crumb texture, crumb structure, crumb softness, flavour relative staleness and shelf life. These dough and/or baked product improving processing aids can be divided into two groups: chemical additives and enzymes (also referred to as baking enzymes).
Chemical additives with improving properties comprise oxidising agents such as ascorbic acid, bromate and azodicarbonate, reducing agents such as L-cysteine and glutathione, emulsifiers acting as dough conditioners such as diacetyl tartaric acid esters of mono/diglycerides (DATEM), sodium stearoyl lactylate (SSL) or calcium stearoyl lactylate (CSL), or acting as crumb softeners such as glycerol monostearate (GMS) etceteras, fatty materials such as triglycerides (fat) or lecithin and others.
As a result of a consumer-driven need to replace the chemical additives by more natural products, several baking enzymes have been developed with dough and/or baked product improving properties and which are used in all possible combinations depending on the specific baking application conditions.
Emulsifiers, applied in baking industry can be roughly divided in crumb softening or dough strengthening agents. Distilled monoglycerides are used mainly for crumb softening. Complexing of the monoglycerides with starch prevents complete recrystallisation of starch, which results in initial crumb softness and/or reduction of crumb firming rate during shelf life of the baked product. For dough strengthening, a few different synthetic analogues of polar lipids are applied, such as DATEM, CSL and SSL. Their effect in breadmaking is to improve dough stability, increase loaf volume and induce a fine and uniform crumb structure. With regard to this latter aspect it should be noted that crumb softening is also included when these emulsifiers are applied. Also reduced stickiness of the dough, improved machinability of the dough, increased loaf volume of the baked product, improved crumb structure, improved crumb softness, improved crispyness of the crust can be reached.
The emulsifiers, due to their polar and apolar moieties, can concentrate at oil-water and gas-water interfaces. In breadmaking the gas cells are initially enclosed in a gluten-starch matrix, but during fermentation gas cells increase in volume and interfaces between gas cells comprise only a liquid film of surface-active material. The endogenous polar lipids of wheat flour are present in these liquid films, as well as the added emulsifiers. It is known that polar diacylglycerols, such as lecithins or DATEM produced from diacylglycerols, have only limited effect in breadmaking, when compared to their monoacylglycerol counterparts.
It is known in the art that certain lipolytic enzymes can be used as DATEM replacers such as for example is disclosed by L. Chirstiansen et al in Proceedings of the Third Symposium on Enzymes in Grain Processing, 25-27 Sep. 2002, p 269-274.
Lipolytic enzymes are enzymes that catalyse the hydrolysis of ester bonds in lipid substrates. Lipolytic enzymes can act upon several types of lipids, ranging from glycerides (e.g. triglycerides), phospholipids, sphingoplipids or glycolipids, such as galactolipids.
Glycerides are esters of glycerol and fatty acids. Triglycerides (also known as triacylglycerol or triacylglycerides) are mostly present in vegetable oils and animal fat. Lipases (EC 3.1.1.3) are defined herein as enzymes that hydrolyse one or more of the fatty acids from lipids, more specifically they hydrolyse the ester bond between fatty acid and hydroxyl groups of the glycerol.
Galactolipids consist of a glycerol backbone with two esterified fatty acids in an outer (sn-1) and middle (sn-2) position, while the third hydroxyl group is bound to sugar residues such as a galactose, for example monogalacosyldiglyceride or digalactosyldiglyceride. Galactolipase (EC 3.1.1.26) catalyses the hydrolysis of one or both fatty acyl group(s) in the sn-1 and sn-2 positions respectively from a galactosyldiglyceride.
Phospholipids consist of a glycerol backbone with two esterified fatty acids in an outer (sn-1) and the middle (sn-2) position, while the third hydroxyl group of the glycerol is esterified with phosphoric acid. The phosphoric acid may, in turn, be esterified to for example an amino alcohol like ethanolamine (phosphatidylethanolamine), choline (phosphatidylcholine). Phospholipases are defined herein as enzymes that participate in the hydrolysis of one or more bonds in the phospholipids.
Lipolytic enzymes comprise for example lipases, galactolipases and phospholipases, such as for example phospholipase A1, A2 and lysophospholipase, depending on the substrate they act upon.
There is a continuing need for improved lipolytic enzymes that can be used as replacers of chemical emulsifiers, such as DATEM, CSL and SSL, in the production of bread.